Least common denominator finds a common number in the denominator of two fractions. 14 can be factored out as 2*7 and 7 is obviously 7*1. So the least common denominator could come from both numbers that have common denominators. In order to attain a common denominator, you need to multiply the 7 by 2 to make 14. So the least common denominator is c. 14.